For AMD cards, set the following environment variables, especially if you have 2GB cards:
GPU_FORCE_64BIT_PTR 0
GPU_MAX_HEAP_SIZE 100
GPU_USE_SYNC_OBJECTS 1
GPU_MAX_ALLOC_PERCENT 100
GPU_SINGLE_ALLOC_PERCENT 100
WHERE DO I WRITE THESE?
Create a .bat file with that inside it. Ummm.......you are a newbie here so I will spell it out.
Create a new text document and paste those setting it in. Then File> Save as>name it something.bat and choose All files in the Save a type field.